Water transport in highly water-permeable membranes is conducted by water-selective pores-namely, water channels. The recent cloning of water channels revealed the water-selective characteristics of these proteins when expressed in Xenopus oocytes or reconstituted in liposomes. Currently, It is as d that the function of water ch ls is to transport only water. We now report the cloning of a member of the water channel that also transports nonionic small molecules such as urea and glycerol. We named this channel aquaporin 3 (AQP3) for its predominant water permeabilit. AQP3 has amino acid sequence Identity with major intrinsic protein (MIP) family proteins including AQPchannel-forming integral membrane protein, AQP-colecting duct, MIP, AQP-ytonoplast intrinsic protein, nodulin 26, and glycerol facilitator (33-42%). Thus, AQP3 is an additional member of the MEP family. Osmotic water permeability of Xenopus oocytes measured by videomicroscopy was 10-fold higher in oocytes injected with AQP3 transcript than with water-injected oocytes. The increase in osmotic water permeability was inhibited by HgC12, and this effect was reversed by a reducing agent, 2-mercaptoethanol. Although to a smaller degree, AQP3 also facilitated the transport of nonionic small solutes such as urea and glycerol, while the previously cloned water channels are permeable only to water when expressed in Xenopus oocytes. AQP3 mRNA was expressed abundantly in kidney medulla and colon. In kidney, it was exclusively immunokoalzed at the baolateral membrane of collecting duct cells. AQP3 may functon as a water and urea exit hanism in antidlure in ollecting duct cells.Water channels have been postulated for the pathway of selective water permeation in highly water-permeable membranes. Recent

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We recently cloned a cDNA of the collecting duct apical membrane water channel of rat kidney, which is important for

Abstract:We investigated the capabilities of a canopy height model (CHM) derived from aerial photographs using the Structure from Motion (SfM) approach to estimate aboveground biomass (AGB) in a tropical forest. Aerial photographs and airborne Light Detection and Ranging (LiDAR) data were simultaneously acquired under leaf-on canopy conditions. A 3D point cloud was generated from aerial photographs using the SfM approach and converted to a digital surface model (DSMP). We also created a DSM from airborne LiDAR data (DSML). From each of DSMP and DSML, we constructed digital terrain models (DTM), which are DTMP and DTML, respectively. We created four CHMs, which were calculated from (1) DSMP and DTMP (CHMPP); (2) DSMP and DTML (CHMPL); (3) DSML and DTMP (CHMLP); and (4) DSML and DTML (CHMLL). Then, we estimated AGB using these CHMs. The model using CHMLL yielded the highest accuracy in four CHMs (R 2 = 0.94) and was comparable to the model using CHMPL (R 2 = 0.93). The model using CHMPP yielded the lowest accuracy (R 2 = 0.79). In conclusion, AGB can be estimated from CHM derived from aerial photographs using the SfM approach in the tropics. However, to accurately estimate AGB, we need a more accurate DTM than the DTM derived from aerial photographs using the SfM approach.